RATTLESNAKE FERN AND ADDER’S-TONGUE. 43 
nate with double rows of sporangia along the midribs. 
Occasionally a plant bears two fertile spikes. The spores 
are abundant, bright yellow, and escape from the cap- 
sules through a narrow transverse slit. The blade is 
noticeably thin and when dried is exceedingly delicate. 
The rootstock is scarcely discernible, the stipe seeming 
to spring from a tangle of thick fleshy roots radiating 
horizontally afew inches underground. Next year’s leaf 
bud is enclosed in a hollow in the side of the growing stipe 
at base, and its tiny stipe encloses a still smaller bud which 
in turn encloses another, the latter destined not to develop 
for three yearsto come. According to Campbell's 
‘‘Mosses and Ferns,” the development of the sporangia 
begins fully a year before the spores are shed. 
Within our limits, this species never has more than a 
single frond, except by accident, but in the West Indies 
it normally appears with two. The author of the “ Ferns 
of Jamaica” remarks, ‘“ There are two fronds to each 
plant, one without and the other with, the fertile division.” 
The writer, who recently collected fine specimens in the 
Blue Mountains of Jamaica, discovered, however, that 
the fern is still true to its habit of producing but one 
frond a year. The frond lacking the fertile division 
proves to be the frond of the preceding year which the 
mild climate allows to remain green until the next frond 
is produced. The scar left by the withering of the fertile 
spike is quite noticeable. 
Another peculiarity of this species is the great disparity 
in the size of fruiting plants and in the large proportion 
of apparently full-grown specimens that are sterile. Some 
bear fruit when but a few inches high, but others near by, 
twice as large, do not. The cause of this sterility in the 
large plants is unknown unless it may be explained upon 
